The present invention relates to pharmaceutical compositions comprising the compound eplerenone as an active ingredient, and more particularly to pharmaceutical compositions containing micronized eplerenone, methods of treatment comprising administering such pharmaceutical compositions to a subject in need thereof, and the use of such compositions in the manufacture of medicaments.
The compound methyl hydrogen 9,11xcex1-epoxy-17xcex1-hydroxy-3-oxopregn-4-ene-7xcex1,21-dicarboxylate, xcex3-lactone (also referred to herein as eplerenone) was first reported in Grob et al., U.S. Pat. No. 4,559,332 that describes and claims a class of 9,11-epoxy steroid compounds and their salts together with processes for the preparation of such compounds. These 9,11-epoxy steroid compounds are described as aldosterone antagonists that can be administered in a therapeutically effective amount to treat pathological conditions associated with hyperaldosteronism such as hypertension, cardiac insufficiency and cirrhosis of the liver. U.S. Pat. No. 4,559,332 contains general references to formulations for the administration of these 9,11-epoxy steroid compounds such as tablets and capsules.
Eplerenone corresponds in structure to Formula I, below: 
Spironolactone, another 20-spiroxane-steroid having activity as an aldosterone antagonist, is commercially available for the treatment of hypertension. Spironolactone corresponds in structure to Formula II, below: 
Spironolactone, however, exhibits antiandrogenic activity that can result in gynecomastia and impotence in men, and weak progestational activity that produces menstrual irregularities in women. Commercial formulations of spironolactone (sold under the name Aldactone(trademark)) contain 25, 50 or 100 mg doses of spironolactone in a matrix comprising, among other carrier materials, calcium sulfate dihydrate as a diluent, maize starch as a disintegrant, povidone K-30 as a binding agent, magnesium stearate as a lubricant, and flavor, colorant, and coating ingredients that include hydroxypropylmethylcellulose and polyethylene glycol 400.
de Gasparo et al., in Journal of Steroid Biochemistry 32 (1B), 223-227 (1989) report the use of spironolactone and epoxymexrenone in receptor binding studies. Those materials, with spironolactone in a commercial formulation with a particle size of 5 microns and the epoxymexrenone at a particle size of 20 microns in a non-formulated composition, were also used in vivo to study excretion of sodium in urine.
The effective administration of eplerenone to a subject has been complicated by the compound""s low solubility and low compressibility as well as by its other physical and chemical properties. Pharmaceutical compositions comprising micronized eplerenone and a pharmaceutically acceptable carrier material, however, have been discovered that can effectively deliver a therapeutically preferred amount of the compound to the subject. In addition, unique combinations of carrier material with the micronized eplerenone have been found that provide still better solubilization characteristics. These combinations of active compound and carrier material have been found to possess improved bioavailability, chemical stability, physical stability, dissolution profiles, disintegration times, safety, as well as other improved pharmacokinetic, chemical and/or physical properties. The present invention comprises these pharmaceutical compositions, unit dosage forms based thereon, and methods for the preparation and use of both.